Spread of chikungunya in the Americas is not slowing

August 31, 2014

The Pan American Health Organization (PAHO) released its latest data on the spread of chikungunya in the Western Hemisphere on Aug. 29. The international agency has received reports of 659,367 suspected, probable or confirmed chikungunya illnesses since the disease was first diagnosed in the hemisphere in Dec. 2013. The total was an increase of 11.8 percent from the prior week.

The various territories and nations voluntarily report their data to the PAHO. Timely reporting continues to affect the accuracy of the data. Dutch St. Martin, for example, has not submitted a reports for 12 weeks. Haiti is six week behind in reporting. Because of the delays in reporting, the data provided by the PAHO is just a lower limit for the actual number of illnesses.

Puerto Rico is reporting different case counts to the PAHO than it is to the U.S. Centers for Disease Control. As of Aug. 29, the commonwealth has seen 1,226 confirmed chikungunya cases and an estimated 4,079 suspected cases. The latest report to the CDC showed Puerto Rico having experienced 217 confirmed illnesses through Aug. 26.

The two nations on the island of Hispaniola have reported 75 percent of the chikungunya cases, despite the illness arriving just five months ago. The Dominican Republic reports that 4.1 percent of its population has been sickened by the mosquito borne virus, 429,492 people. That report is as of last week.

Haiti is six weeks behind in its reports. Its last count of chikungunya illnesses was 64,709. The Dominican Republic and Haiti share a border. Based upon social media reports from medical professionals in Haiti, it appears that the number of cases is grossly understated.

One unusual aspect of the chikungunya outbreak is how it is spreading in Central America. El Salvador is reporting a large and growing outbreak, with 8,040 cases as of last week. In marked contrast, its two neighbors, Guatemala and Honduras are reporting none. It is an anomaly which has yet to be explained.